Juvenile crime imposes enormous costs on victims, on society, and on juvenile offenders themselves. However, research assessing the efficacy of interventions for young offenders show, on average, only small effects on recidivism, substance abuse, and other behavioral outcomes. A major problem with existing interventions is that they tend to neglect individual differences in motivation and readiness to make positive changes. We propose to use an empirically validated model of behavior change, the Transtheoretical Model (TTM), and expert system technology to develop a computerized intervention designed as an adjunct to traditional juvenile justice programs. The intervention will deliver assessments and individualized feedback matched to readiness to stay out of trouble with the law and reduce substance use. It will also generate counselor reports that summarize the youth's feedback and present concrete, easy-to-implement strategies counselors can use to reinforce stage-matched concepts. The goals of this Phase I project are to develop and validate TTM measures for reducing marijuana and alcohol use among juvenile offenders (to supplement measures already developed for staying out of trouble with the law);to develop the baseline portion of a computer-administered, interactive, multimedia expert system program;and to test the feasibility of this approach to intervention. Juvenile offenders will participate in focus groups to generate ideas for the TTM measures (n=32) and to provide feedback on the intervention materials (n=32);cognitive interviews to ensure TTM instructions and questions are interpreted as intended (n=8);usability tests to ensure that the expert system intervention is easily navigable and provides a coherent intervention experience (n=8);and an anonymous survey for measure development and validation (n=200). Finally, 60 court- and system-involved youth will participate in a feasibility trial and receive the intervention;their counselors will receive the counselor reports. The feasibility of this approach will be established if: 1) we are able to deliver the intervention as planned to at least 90 percent of trial participants in a range of juvenile justice programs and settings;2) participants provide positive ratings of the acceptability and usefulness of the interactive session;3) counselors provide positive ratings of the helpfulness of the counselor reports;and 4) the intervention yields statistically significant pre-post changes on proximal measures of change-namely, youths'assessments of the benefits of staying out of trouble with the law, and the benefits of reducing substance use. PUBLIC HEALTH RELEVANCE: Juvenile crime imposes enormous costs on victims, on society, and on juvenile offenders themselves. We propose to use an empirically validated model of behavior change, the Transtheoretical Model (TTM), and expert system technology to develop a computerized intervention designed as an adjunct to traditional juvenile justice programs. The intervention, which delivers assessments, individualized feedback, and counselor reports matched to youths'readiness to stay out of trouble with the law and reduce substance use, has the potential to increase programs'responsivity to youths'needs;make more efficient use of scarce program resources;and improve outcomes.